Halophile algae, especially of the Dunaliella type, grow in nature in aqueous media having a high salt content, such as salterns. Such algae can be cultivated in order to obtain a convenient source of lipids, carotenes, proteins, glycerol and of hydrocarbon mixtures essentially similar to fossil oil. See, for example, U.S. Pat. No. 4,115,949. For such cultivations, the conditions must be suitably adapted.
One of the main limitations in the cultivation of halophilic algae in salty solutions is the velocity of transfer of carbon dioxide from air into the solution. Exchange with the atmosphere results in a surface layer, which serves as source of carbon dioxide for lower layers of higher alkalinity, which have become depleted of carbon dioxide due to the metabolism of the algae. A further limiting factor is the low velocity of conversion of carbon dioxide to H.sub.2 CO.sub.3 when dissolved in brine. Satisfactory conditions of cultivation can be provided by replenishing evaporated water in a suitable manner and by adding certain additives adapted to further the rate of growth of said algae and, if required, by adding fertilizers.